A method for guiding an AI agent from an idea to verified software through specifications, risk-based review, recorded decisions, and staged work. Spec-driven development means writing requirements that guide and check implementation.

Use it to route a substantial change through request, specification, clarification, review, implementation, and verification stages.

Long autonomous coding runs can produce code that passes tests but does not meet the request; this process keeps intent and decisions visible.

asdd — Skill for Claude Code and Codex by ericrisco/rsc-harness

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo

git clone --depth 1 https://github.com/ericrisco/rsc-harness

agentmods

npx agentmods add skills/ericrisco/rsc-harness/asdd

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

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Your own site

<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/asdd"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/asdd/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/asdd"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/asdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 145 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,948 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00145	$0.03948
Opus 5.5	$0.00058	$0.01579
Sonnet 5.5	$0.00029	$0.00790
Haiku 4.5	$0.00015	$0.00395

Measured yesterday against content hash c2a86bcb586c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

asdd scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/asdd/SKILL.md · 186 lines

How it starts

The opening of the file, as written. The whole thing — 186 lines — stays where its author put it; the contents beside it link to each section on GitHub.

asdd — Agent Spec-Driven Development

The front door for letting an agent build for hours without coming back with a Frankenstein: intent in, shipped-and-verified software out, every decision recorded in 02-DOCS/wiki/sdd/.

Why it exists. Classic SDD reviewed at the end. On paper it checked the spec; in a long autonomous run, the only thing that bit for hours was the test — and tests prove the code works, not that it does what was asked (a real run: 8 hours, 4,500 green tests, and a dropped token plus a QR nobody requested). ASDD keeps the phases and changes two things: the spec must prove itself, and the review moves inside every task, scaled by risk. The human stops reviewing everything and only takes the decisions the agent must not take alone.

This skill does not do a phase. It names the method, reads the register, places the request on the map and hands off. Each phase skill points at the next one.

The five stages

  request ─► decisor (answer · ftd · asdd)
                         │ asdd
 1. BASE ─────► constitution + REVIEW.md                 (once per project)
 2. SPEC ─────► specify (4 questions + out of scope) ─► clarify (gap checklist)   ◄── HUMAN APPROVES
 3. PLAN ─────► plan ─► tasks (criterion · risk forecast · check) ─► analyze
 4. LOOP ─────► per task, in implement:
                 a build + self-check   b rsc risk        c review by tier
                 d verify findings      e mandatory controls
                 f fix (max 3 rounds)   g fix & record  ─or─  park ─► DECISION QUEUE ◄── HUMAN
 5. CLOSE ────► verify against main + rollback plan · closing review (whole branch vs spec) · explainer
    SHIP ─────► remote: PR (self-merge only tier 0-1 + green CI + no blocking entry)  │  no remote: park  ◄── HUMAN
    LEARN ────► finding outcomes · reverts → reviewer cases · repeated finding → rule

Stage	Phase skills	Writes
1 Base	`../constitution/SKILL.md` (also drafts `REVIEW.md`), `../sdd-init/SKILL.md`	`constitution.md`, `REVIEW.md`, `config.yaml`
2 Spec	`../specify/SKILL.md` → `../clarify/SKILL.md`	`specs/<slug>.md`
3 Plan	`../plan/SKILL.md` → `../tasks/SKILL.md` → `../analyze/SKILL.md`	`plans/<slug>.md`, `analysis/<slug>.md`
4 Loop	`../implement/SKILL.md`, calling `../verify/SKILL.md` and `../review/SKILL.md` per task	`progress/<slug>.md` (with `## Decision queue`), `decisions.md`
5 Close	`../verify/SKILL.md` (closing mode), then `../review/SKILL.md` (closing review, on what will ship), `../ship/SKILL.md`	`verifications/<slug>-<date>.md`, `reviews/<slug>.md`, the PR or parked branch
on demand	`../debug/SKILL.md` · `../worktrees/SKILL.md` · `../parallel/SKILL.md`	—

Read the full file on GitHub · 186 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

yesterday Changed · +2 lines c2a86bcb586c
2d ago First seen · 184 lines · 145 tokens per session scan A 16f4618d31ea

Subscribe to this mod's changes

asdd is a skill published in the GitHub repository ericrisco/rsc-harness (503 stars, last pushed 2d ago), licensed MIT. It adds 145 tokens to every session and 3,948 once invoked, about $0.0006 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-11-04.

Building agents Claude Code Planning agent-skills agentic-ai ai-agents ai-coding asdd cli plan review sdd spec workflow

asdd next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
asddericrisco/rsc-harness	Skill	503	2d ago	MIT	A	145	Claude Code, Codex
ospecclawplays/ospec	Skill	390	2mo ago	MIT	A	26	Claude Code, Codex
ospec-changeclawplays/ospec	Skill	390	2mo ago	MIT	A	18	Codex
receiving-code-reviewandreaswasita/copilot-agents-dojo	Skill	54	2mo ago	MIT	A	14	Claude Code, Codex
code-reviewandreaswasita/copilot-agents-dojo	Skill	54	2mo ago	MIT	A	13	Claude Code, Codex
executing-plansandreaswasita/copilot-agents-dojo	Skill	54	2mo ago	MIT	A	17	Claude Code, Codex
pr-workflowandreaswasita/copilot-agents-dojo	Skill	54	2mo ago	MIT	A	17	Claude Code, Codex